Avalanche Forecast

Issued: Jan 24th, 2015 8:51AM

The alpine rating is high, the treeline rating is high, and the below treeline rating is considerable. Known problems include Storm Slabs, Persistent Slabs and Deep Persistent Slabs.

esharp, Avalanche Canada

Cariboos.

High freezing levels with rain and strong winds mean that the snow pack may take time to stabilize. Conservative decision making is still recommended.

Summary

Confidence

Good - Due to the number and quality of field observations

Weather Forecast

A second warm wet weather system will hit the coast on Sunday. A week ridge of high pressure will protect the interior from the brunt of this system however the Cariboo region will see some light precipitation. Warm temperatures and moderate to strong SW winds will persist through until Tuesday .

Avalanche Summary

Widespread avalanche activity was reported on Saturday with natural avalanches up to size 3. Forecast warm temperatures mean that rain could fall on all but the highest peaks. This. combined with high winds is a recipe for an avalanche cycle, especially when you throw in a couple of prominent weak layers. I anticipate an active cycle to continue tomorrow. Previous avalanche activity during and after the last storm system was widespread, with avalanches releasing up to size 3 on a variety of aspects and elevations.

Snowpack Summary

Between 20 and 35 cm of new snow (and possibly rain at lower elevations) fell in the last storm which I suspect is rapidly settling into a soft slab. This new snow sits upon a moderately dense upper snowpack. A weak layer of surface hoar lies buried between 60 and 90 cm below the surface, and may sit above a crust, particularly on south-facing slopes. This "mid-January" weak layer is widespread and has been the main focus for recent avalanche activity. I suspect that it will continue to produce avalanches through the weekend as the snow pack adjusts to the recent snowfall and continued warm temperatures. The still problematic mid-December surface hoar/crust layer is now buried anywhere from 60 to 120cm below the surface and continues to pop in snow pack tests at and below treeline. Avalanches were reported to have stepped down to this layer during and after the most recent storm cycle. With additional loading and warm temperatures, I'd continue to treat this layer with respect and suspicion, particularly in the 1700-1900 m elevation band. A release on this layer would have very high consequences.

Problems

Storm Slabs

Warming temperatures and rain with high winds will likely cause avalanches from sufficiently steep terrain in a number of places. At lower elevations the new snow may become saturated and form loose wet avalanches.

Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 4

Persistent Slabs

A weak layer of surface hoar is buried between 60 and 90 cm below the surface, on south aspects this layer sits above a crust. This layer produced has produced large avalanches and it will take some time to adjust to the new snow and warm conditions.

Watch for whumpfing, hollow sounds, shooting cracks or recent avalanches.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

2 - 5

Deep Persistent Slabs

A weak layer buried mid-December is still producing dangerous avalanches over a month after it was first buried. Particularly for slopes around treeline, there is a danger for a small avalanche to step down to this layer increasing the consequences.

Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Possible

Expected Size

3 - 6

Valid until: Jan 25th, 2015 2:00PM